This invention relates to an instrument for gathering tissue for biopsy. More particularly, this invention relates to an instrument of a type known variously as a biopsy needle or cannula and used to gather tissue, and particularly soft tissue such as bone marrow, from living persons or animals for pathological study.
Such instruments are known generally and have been in wide use prior to the present invention. Examples may be found in the literature and from medical supply houses, and may include instruments such as are shown in Hallac U.S. Pat. No. 3,605,721; Lingley U.S. Pat. No. 2,850,007; and a series of United States Patents issued to Khosrow Jamshidi. In use, difficulties may be encountered with the loss of tissue specimens from within the instruments. More particularly, it is often difficult for a tissue specimen to be retained within an instrument during withdrawal of the instrument from the body of tissue into which it has penetrated, as the tissue is not fully separated from the living organism of which it forms a portion. Such loss of specimens is frustrating to the physician seeking to gather the tissue, and may subject a patient to needless imposition as repeated attempts are made to gather a specimen.